The use of communication devices in windy conditions is an every-day occurrence for people around the world, but the microphone pickup of wind noise often interferes with effective communication. A basic characteristic of wind noise is that it is highly dynamic and non-stationary in time, much like the characteristic of speech, making it difficult to separate the wind noise from a noisy speech signal. Current state-of-the art headsets, handsets, car kits and the like utilize multiple microphones in array configurations, along with noise reduction algorithms, to reduce or remove acoustic background noise. Recognizing the fact that wind noise is heavily weighted toward the low frequencies, the interference of wind noise is often addressed by using high-pass filters in single-channel methods (sometimes in an adaptive manner). These methods reduce the audible wind noise, but such filters cut all low frequency sounds including that of the desired speech signals, producing a deterioration of sound quality and a reduction of speech intelligibility.
Wind noise is created at a microphone's input by the turbulent pressure fluctuations developed by moving air. These pressure fluctuations are effectively uncorrelated at multiple, spaced apart, microphones because the spatial coherence of the fluctuations decays rapidly with distance. Thus, wind noise picked up by spaced apart microphones is essentially uncorrelated, while the desired signal is correlated.